Eight motorists a day are showing up to a tyre shop in Tauranga with busted and damaged wheels caused by potholes.

Andrea Lee who estimates it will cost her about $1000 to fix two of her tyres and rims after she hit a pothole on the Kaimai Range on Friday night - an experience that left her "freaking out" and stranded on the side of the road with her 11-year-old son.

Waka Kotahi NZ Transport Agency told the Bay of Plenty Times it had received 14 requests or complaints about potholes damaging vehicles on the stretch of road that night, with the transport manager saying anecdotally about 20 cars were affected.

It said contractors were on site within an hour of being notified, putting traffic management in place to avoid further risk.

Police issued a warning on Friday night after a reported pothole punctured the tyres of various vehicles traversing State Highway 29 over the Kaimai Range. The Bay of Plenty region also received more than 120mm of rain across 72 hours in the weekend.

Lee was on her way back from dropping off her daughter, 7, in New Plymouth when it happened.

Lee said her car did not come with a space saver wheel, but rather a "bottle of gunk and a compressor", which could not fix the tyres.

The damaged tyre rim. Photo / Andrew Warner

She had to leave her car on the side of the road overnight until she was able to replace her two tyres with borrowed space savers the next day. She got a ride home with her flatmate that night.

"It was just loud. I knew what had happened straight away and there were already so many cars to the left-hand side.

"It's very inconvenient. I don't know how long it's going to take but I am probably looking at over $1000 to get my wheels fixed."

She said her insurance provider did not cover damage caused by potholes and planned to send Waka Kotahi the repair costs.

"I can't afford to wait until they pay for it, so I am struggling myself to pay for it. So I can get the receipts to give to them. It's honestly the biggest pain."

Mag Master Tauranga manager Kevin Browne said on average he was seeing eight customers a day whose wheels had been damaged by potholes and he was working fulltime fixing bent wheels.

He said some were not repairable because of safety issues and he feared motorists were not getting their tyres checked.

''If you are driving around with a dent in your wheel it is just a matter of time. It's an accident waiting to happen."

Browne had worked in the industry for 18 years and ''we have been really, really busy with pothole work''.

''It's the worst I've seen it. It's diabolical.''

Hamilton resident Ruth Ellis, whose wheel was also damaged after hitting the pothole on Friday, described the situation as "frustrating".

She pulled off to the side of the road after hitting the pothole around 5pm. Her son had to change a tyre in the pouring rain.

Ellis contacted Waka Kotahi about covering the cost of the tyre damage and was advised to contact her insurance company.

She said would have to borrow money from her brother as her benefit would not cover the cost of repairs and a new tyre.

It had done "pretty hefty damage" to one tyre and the rim, and the car's suspension, she said.

"There were at least 25 cars we saw that had been affected by the one pothole. My son changed the tyre and we went off again - round the corner there were even more cars impacted by that one pothole."

She said the pothole was dangerous and needed to be repaired immediately.

Tauranga mum Andrea Lee was one of the drivers who hit the pothole while driving over the Kaimai Range on Friday. Photo / Andrew Warner

Mount Maunganui resident Amy Jenkins said the multiple incidents on Friday did not come as a surprise to her.

She has recently paid $350 to replace two of her car tyres after driving over a large pothole on the Kaimai Range on Tuesday, September 20.

She said the potholes were "certainly an issue" and felt the stretch of road was "not up to standard".

Figures show 26 complaints were made to Waka Kotahi about potholes between Saturday and Monday nationwide.

So far Waka Kotahi had received 14 requests or complaints about potholes damaging vehicles on the Kaimai Range on Friday.

Waka Kotahi regional manager of maintenance and operations Rob Campbell said it was not possible to know the exact number of cars affected as there was no obligation to report it. Anecdotally, it appeared around 20 were affected, he said.

Campbell said potholes caused "significant disruption" for those driving on the stretch of road last Friday, describing it as a "challenging and stressful situation for motorists in the wet conditions".

He said contractors were on site within an hour of being notified, putting traffic management in place to avoid further risk.

Bay of Plenty MP Todd Muller. Photo / George Novak

Remedial work would get under way on SH29 tonight, which included resurfacing the "problem area".

Next week programmed chip sealing work, originally planned for late next month, would begin helping improve the condition of the road, he said.

Complaints made to Waka Kotahi claiming the road's condition had caused damage to a vehicle were assessed on a "case-by-case basis".

Drivers were expected to have insurance for their vehicles in the event of any damage that may occur on the road, he said.

"Their insurer should be their first point of contact where any damage has occurred and, if appropriate, their insurer would then be in touch with Waka Kotahi."

He said the transport agency was now undertaking the country's "largest-ever road renewal season" to improve the overall state highway road condition.

From late September through to April next year, more than 700 lane kilometres of state highway would be resealed or rebuilt throughout Waikato and Bay of Plenty – more than 13 per cent of the region's network.

Tauranga City Council transport network operations manager Tony Bonetti said significant rain over the past two months had contributed to an increase in potholes on the local roading network.

"The increase in potholes has stretched our resources; and we have had to prioritise urgent repairs of dangerous potholes as quickly and safely as possible, as they are a serious hazard to road users."

Potholes classified as less urgent were repaired as soon as resources became available, she said.

She urged drivers to report potholes to council, saying it helped staff understand where they were.

Bay of Plenty MP Todd Muller said "a number" of residents had complained to him directly about potholes in Pāpāmoa and on the region's state highways.

Some of their cars had been damaged by a pothole on Pāpāmoa Beach Rd as it turned into Maranui St, he said.

"It's just sheer frustration that the local government and central government just can't get the basics right," he said.

Western Bay of Plenty District Council senior transportation engineer Calum McLean said winter had seen a "substantial increase" in the number of potholes reported across the Western Bay.

He said 47 complaints were made to council in relation to potholes on Western Bay's roading network in September, at least double that reported during previous months.

A pothole on State Highway 33 near Paengaroa. Photo / Andrew Warner

How heavy rain causes potholes

Waka Kotahi regional manager of maintenance and operations Rob Campbell said winter always took a toll on the roads and the damage caused by particularly heavy rain recently had been "especially bad".

The Bay of Plenty received more than 120mm of rain across 72 hours over this weekend alone, he said.
 
"This winter has seen a significant increase in potholes across the country, compared to the past three years. This is down to a combination of current network conditions and the wet winter."

He said potholes could occur for an number of reasons, but water was the primary cause and they could "appear quickly" after heavy rain.

"With our older pavements, if there is a crack in the road surface, or a displaced stone, it will allow water to sit in the road surface. As vehicles drive over the ponding water, tyres create hydraulic pressure, forcing the water down into the pavement."

He said over time as vehicles continue to run over the pothole it would grow as weakened areas break off.

Sections of road that are due for renewal - like part of SH29 - were more prone to potholes as the pavement and surface were "weaker and starting to fail".

Potholes were required to be repaired within 48 hours of being identified by the contractor.

Western Bay pothole hotline

* Potholes can be reported to its Freephone line, 0800 WBOPDC (0800 926 732) or (07)5718008. Phone lines are open 24/7.